The correct answer is - He stands between the protagonist and her goal.
Creon is not your typical antagonist - he isn't actually a villain, he is not evil. The only thing he does is not allow Antigone to have what she wants. She wants to give her deceased brother a proper burial, but Creon is against that because the brother was a traitor. This is why he forbids her from doing that and this causes various tragedies in the play.
